Seamless screen pipes

ABSTRACT

A seamless screen pipe comprising a seamless tubular screen made of organic fiber and a metal film formed on the surface of constituent yarns of the tubular screen with the meshes thereof retained; and a method for producing a seamless screen pipe comprising the step of plating a metal film on the surface of constituent yarns of a seamless tubular screen made of organic fiber with the meshes thereof retained.

[111 3,871,411 5] Mar. 18, 1975 1 SEAMLESS SCREEN PIPES [75] Inventors: Takayuki Sato; Hideo Ota; Jiro Yokoyama, all of Osaka; Takashi Nakamura, Nara, all of Japan [73] Assignee: Satosen Company Limited,

Osaka-shi, Japan [22] Filed: Sept. 7, 1972 [21] App]. No.: 287,017

[52] US. CL... 138/178, 204/21 [51] Int. Cl. F161 9/00 [58] Field of Search; 138/177, 178; 204/21, 25,

[56] References Cited UNITED STATES PATENTS 1,137,405 4/1915 Jennings 138/178 X 11/1933 Rafton 204/21 X 3,540,988 11/1970 Wells et al. 204/24 FOREIGN PATENTS OR APPLICATIONS 5,348 5/1902 United Kingdom 204/21 2,703 7/1900 United Kingdom 204/21 Primary Examiner-Jerry W. Myracle Attorney, Agent, or Firm-'Wren and McGeady [57] ABSTRACT A seamless screen pipe comprising a seamless tubular screen made of organic fiber and a metal film formed on the surface of constituent yarns of the tubular screen with the meshes thereof retained; and a method for producing a seamless screen pipe comprising the step of plating a metal film on the surface of constituent yarn-s of a seamless tubular screen made of organic fiber with the meshes thereof retained.

3 Claims, 5 Drawing F ignres mm] mm mm 3.871941 1 Fig.2

[:IEIEIUEH] SUEDE] DUCICHIHII SEAMLESS SCREEN PIPES The present invention relates to a seamless screen pipe which is useful for screen printing purposes and a method for producing the same.

A method for producing a seamless screen pipe has heretofore been known which employs a matrix in the form of a roll having in its surface a great number of small concavities disposed in-reticular arrangement and filled with electrically insulating material. According to this methd, a metal film is plated on the surface of the matrix and the plated film is slipped off the matrix.

However, the seamless screen pipe obtained by the conventional method has the drawback of being low in flexibility and susceptible to damage, because it com prises a thin plated metal film. Accordingly, the conventional product has to be handled with special care when it is put to use, while not infrequently it gets damaged during use and is not serviceable for a long period. In addition, the conventional product requires complex steps for production and needs great skill and long time in removing the deposited film from the matrix. The conventional method gives not a few unacceptable products, and requires high precision in machining the surface of the matrix to form a great number of small concavities therein in regular reticular arrangement, rendering the matrix costly. Formass production, a great number of such expensive matrixes have to be provided, which results in a high manufacturing cost. Since the product is fragileas described above, it is impossible to increase theratio of open area.

An object of this invention is to provide a seamless screen pipe which has high mechanical strength and suitable fexibility and which is durable and very easy to handle for use.

Another object of this invention is to provide a seamless screen pipe which is easy to manufacture and highly amenable to mass production and which can therefore be provided inexpensively.

Another object of this invention is to provide a seamless screen pipe which has an increased ratio of open area.

These and other objects of this invention will become more apparent from the following description.

The seamless screen pipe of this invention comprises a seamless tubular screen made of organic fiber and a metal film formed on the surface of constituent yarns of the tubular screen with the meshes thereof retained. The present seamless screen pipe has the flexibility of a tubular screen made of organic fibers in combination with the rigidity of metal to give a suitable nerve. Accordingly the seamless screen pipe is more excellent in mechanical strength and flexibility than theconventional seamless screen pipe comprising a plated metal film. Consequently, the seamless screen pipe of this invention is not easily broken or torn during use and is durable during a long period of use and very easy to handle The conventional metal screen pipe must be at least about 100 u in the thickness of metal film, otherwise the pipe would be too soft and weak to use and would be deformed, whereas with the screen pipe of this invention whose base material is made of a tubular screen the deposited metal film which a thickness of not greater than 80 t, usually not greater than 40 u, assures satisfactory use. For this reason, it is very economical in that it requires a small amount of metal and is highly productive because of a short period of time for plating. Since metal is deposited on the tubular 2 screen according to this invention, very fine and uniform apertures can be formed. It is even possible to increase the maximum rate of open area. For instance, whereas the conventional method acheives a maximum rate of open area of as low as 20 percent in the case of a mesh/inch screen, the method of this invention attains a maximum rate of 50 percent in the same screen.

The rate of open area is determined by the formula ar=h (h +2R) X100 wherein a is rate of open area, h is length of one side of opening, and 2R is diameter of metal-coated yarn of screen pipe (see FIG. 2). Indeed, the present invention assures mass production, overcoming the disadvantages of the conventional method in which the matrix is subjected to plating and which involves complex steps entailing the difficulty in removing the product from the matrix and provision of a great number of expensive matrixes. s r

The features of this invention will be described below with reference to an embodiment shown'in the drawings, in which FIG. 1 is a perspective view showing an embodiment of this invention;

FIG. 2 is an enlarged fragmentary view of FIG. I with part broken away;

FIG. 3 is a plan view in development showing the selvage of a tubular screen in a plain weave;

FIG. 4 is a fragmentary enlarged view illustrating the selvage as shown in FIG. 3 wherein warp yarns of dif ferent properties are mixedly woven; and

FIG. 5 is a fragmentary enlarged view showing the selvage in FIG. 4 from which the warp yarns of different properties mixedly woven have been romoved.

With reference to FIGS. 1 and 2, there is shown a seamless tubular screen made of organic fibers 1 on which is deposited a thin metal film 2. The seamless tubular screen 1 made of organic fiber is exactly identical in construction to a flat screen conventionally used for screen printing, except that it is tubular. The tubular screen 1 may usually be those of 60-1 ,000 mesh/inch having openings whose one side is larger than 20 p. in length. For instance, tubular screens of lOO 300 mesh/inch are suitable for textile printing. The length h of one side of the opening may be l50 to p. in the case of screens of I00 mesh/inch, or 50 to 60 p. in the case of screen of 300 mesh/inch. Constituent yarns la of the tubular screen 1 are monoor multi-filament yarns. Spun yarns are not suitable for constituent yarns la, because fluffs will render the apertures of screen indistinct. The constituent yarns Ia may suitably be yarns of a wide variety of synthetic fibers, for example, of polyester, polyamide, polyacrylonitrile, polyvinyl i chloride, polyvinylidene chloride, polyethylene, polypropylene, polyvinyl alcohol, polyurethane, etc. Besides these, silk yarns and artificial silk yarns are also employable. Among these examples, polyester fibers,

polyamide fibers and silk can be made into elongated thin filament yarns and are suitable for high-mesh fabrics.

The seamless tubular screen 1 is woven or knitted of filament yarns of these fibers. A hollow weave loom is used for weaving and a circular knitting machine is used for knitting. Most suitably, the pattern of fabric is a plain weave.

When the filament yarns are woven by a hollow weave loom into the tubular screen 1 in a plain weave,

there arise irregularities in the mesh pattern of its sel- 'vage due to the presence of massed warp yarns. Insofar as such irregularities are small, a fabric with such selvage may be used without trouble, while pronouced irregularities will be corrected in the following manner.

FIG. 3 shows the texture of a tubular screen in a plain weave at and near its selvage. The screen includes warp yarns 4 among which closely arranged warp yarns 4 in the selvage 3 provide meshes 5 which are smaller than meshes 5' in the other portion. In such case, warp yarns 4', 4' and 4, 4 are removed from among the massed warp yarns 4 whereby as shown in FIG. 5 the size of the meshes 5 is made equal to that of the other meshes 5' with the difference between the meshes 5 and 5 eliminated. For this purpose, the main body of the fabric is first woven with yarns including warp yarns 4a, 4a and 4a, 4a of different properties which constitute the above-mentioned massed yarns 4, 4 and 4', 4', the yarns 4a being soluble or decomposable by treatment with hot water, acid, alkali or solvent so as to be removed after weaving (see FIG. 4). Only the warp yarns 4a, 4a and 4a, 4a of different properties incorporated in the fabric will then be removed from the fabric by after-treatment, whereby the mesh pattern can be corrected as seen in FIG. 5.

In order to keep the warp yarns 4 and filling yarns 6 in accurate position at their intersections of the fabric, an even number of at least two yarns of different properties are mixedly woven into the fabric as the warp yarns 4a.

In the case where water-soluble vinyl yarns are used for the warp yarns 4a of different properties, the warp yarns 4 and filling yarns 6 constituting the plain weave fabric are water-insoluble yarns. If the fabric main body is made of alkali resistant yarns such as polyamide and acrylic yarns, a material readily decomposable or soluble in alkali such as polyester is used for the warp yarns 4a of different properties. If the fabric main body is made of acid resistant fibers as of polyester, the warp yarns 4a of different properties are those made of a material such as polyamide which is corroded with acid.

The tubular screen 1 obtained by knitting or weaving tends to vary in diameter. It is therefore preferable to improve dimensional stability and accuracy by heat setting or some suitable means prior to the deposition of metal film. Heat setting is conducted by fitting the tubular base screen 1 around a smooth-surfaced roll of a predetermined outer diameter such as a chromium plated iron roll, brass roll, resin-coated roll or the like. Hot water or hot air is used as a heating medium.

A thin metal film 2 is deposited on the surface of the constituent yarns of the tubular base screen l with the mesh pattern thereof retained. Usually, the metal film 2 is plated on the base screen 1 to a thickness of /a to l/lO the length H of one side of its opening (see FIG. 5) and about 5 to 80 u. The metal film may be deposited on the base screen 1 by any method. There are three representative methods for this purpose:

a. Chemical plating to deposit a thin metal film of a predetermined thickness on the tubular base screen 1,

b. Chemical plating to form a thin metal coating (about 0.5 to 5 u in thickness) on the tubular fibrous base screen 1 to render the screen 1 electroconductive and subsequent electroplating to deposit a thin metal film 2 of a predetermined thickness, and

0. Vacuum plating to form a thin metal coating on the tubular fibrous base screen 1 to render the screen 1 electroconductive and subsequent electroplating to deposit a thin metal film 2 of a predetermined thickness.-

Of the methods (a) to (c), the method (b) adopting chemical plating and electroplating takes a shorter time for plating and uses a correspondingly smaller amount of expensive reducing agent as compared with the method (a) by which the metal film is formed solely by chemical plating. Moreover, an expensive vacuum plating apparatus as employed in the method (c) can be dispensed with. Accordingly, the method (b) is the most suitable of the three for the deposition of metal. Chemical plating, and vacuum plating and subsequent electroplating may all be conducted by conventional method.

. For example, in practicing the chemical plating in methods (a) and (b), the tubular base screen 1 is first etched with an inorganic chemical such as, sulfuric acid containing potassium dichromate, as required. With some kinds of fiber, it is difficult to roughen the surface suitably over the entire area. In such case, the tubular base screen 1 is physically swollen with an organic solvent prior to etching, which assures a suitable etching effect uniformly over the entire area. For polyester fibers, for instance, such treatment prior to etching is conducted by immersing the base screen 1 in a solution prepared by dissolving a small amount, preferably not more than 5 wt percent, of caustic soda in a 10 to 20 wt percent aqueous solution of m-cresol, ochlorophenol or the like (hereinafter all percentages are by weight). This treatment is conducted at room temperature for 2 to 5 minutes for dewaxing and swelling. Swelling treatment for polypropylene fibers isconducted in an organic solvent bath comprising an alkaline emulsion and hydrophilic solvent such as acetone or methanol, the alkaline emulsion being prepared by adding l0 to 20 percent of an organic solvent such as decalin, tetralin or the like to a 5 to 20 percent aqueous solution of caustic soda and further adding 2 to ID g/liter of a surface active agent to the resulting mixture. The swellingtreatment is conducted at 50 to 60C for 10 to 40 minutes. For polyamide fibers, phenols, formic acid, glacial acetic acid or the like is used as an organic solvent. It is particularly preferable to conduct the swelling treatment by immersing the material in a 20 percent aqueous solution of formic acid at room temperature for 5 to 20 minutes. The screen with the constituent yarns thus swollen is subjected to etching in usual manner as already described.

After etching treatment, the tubular base screen 1 is washed with water and then sensitized in a usual manner. An activating catalyst is then deposited on the base screen 1 in a conventional manner. The treating solution for activation predominantly comprises palladium chloride and hydrochloric acid, or it may be composed of main ingredients of stannous chloride and hydrochloric acid, with palladium chloride added thereto when so desired.

The tubular base screen 1 thus sensitized and carrying the activating catalyst further deposited thereon is dried and thereafter immersed in a chemical plating bath for chemical plating. Chemical plating may be conducted in usual manner using nickel, copper, cobalt or the like as a plating metal.

Metal is deposited on the activated surface of the fibrous base screen 1 immersed in the chemical plating bath. The coating thus deposited by chemical plating is intended to impart electroconductivity to the base screen 1 and it is not necessary to form a very thick deposit. In the case of method (a) which uses chemical plating alone, the thickness of the chemically plated coating may be 5 to 80 a, while when method (b) is adopted by subsequently conducting electroplating, the

1 chemical coating need not be so thick but may be about 0.5 to 5 p. to obtain a combined thickness of 5 to 80 p. when the base screen 1 is finally subjected to electroplating.

The surface of the base screen 1 chemically plated and thereby rendered conductive is further coated with electroplated metal. Electroplating may be conducted in usual manner using nickel, copper, chrominum or like plating metal.

The base screen 1 is preferably fitted around a nonconductive roll when subjected to chemical plating and electroplating. Employable as the nonconductive roll is a resin roll which is made of a nonconductive material. A conductive iron roll coated with a nonconductive film can also be used.

In the case where the tubular base screen 1 is heat-set while being fitted around a nonconductive roll, the base screen can be subjected to chemical plating without being slipped off the roll. When required, electroplating can be conducted on the base screen 1 in the same state.

The seamless screen pipe of this invention comprises a tubular base screen and a metal film formed on the surface of the base screen and has suitable flexibility derived from the base screen and suitable rigidity attributable to the metal film. The seamless screen pipe is used, for example, as a material for seamless screen pipe for textile printing and general printing purposes. More specifically, the seamless screen pipe of this invention is coated with a dichromic acid photosensitive solution and a positive original is then printed on the sensitive coating, followed by developing and plate making, whereby a seamless screen pipe for textile printing or for other printing purposes is obtained. The plate making can be conducted by photomechanical process as above and other conventional methods.

EXAMPLE l Warp yarns and filling yams, each of which is a 16 denier, mono-flament polyester yarn having a diameter of 40 n, are woven by a hollow weave loom in a plain weave to produce a seamless cylindrical base screen, 1,400 mm in length and 152 mm in outer diameter, in which the warp and filling yarns are spaced apart by 200 ,u to define square meshes. The base screen is immersed in a bath containing 80 percent of sulfuric acid, 0.5 percent of fluorine-type surface active agent and a saturated amount of potassium dichromate at 80C for minutes to effect etching. The base screen is then immersed in a bath containing 30 g/liter of stannous chloride and 40 cc/liter of hydrochloric acid at room temperature for 2 minutes to sensitize the screen. After washing with water, the sensitized screen is immersed for activation in a bath containing 0.1 g/liter of palladium chloride and 0.2 cc/liter of hydrochloric acid as the main ingredients at room temperature for 1 minute. The screen is then washed with water and thereafter immersed in a bath (pH 4.5) containing 30 g/literof nickel sulfate, 20 g/liter of sodium phosphite, 15 g/liter of sodium acetate and 15 g/liter of sodium citrate at 80C for 4 minutes to coat the entire front and rear faces of the base screen with a nickel film of about 0.5

u in thickness. After washing with water the coated base screen is fitted around a rotary polyvinyl chloride roll having an outer diameter of 151 mm, with lead wires fixed to the opposite ends of the base screen respectively and subjected to electroplating in a bath (pH 4.0) containing 300 g/liter of nickel sulfamate, 5 g/liter of nickel chloride, and 30 g/liter of boric acid for 90 minutes, under the conditions of C and 3 A/dm to coat the screen with an electroplated nickel film of about 20 a in thickness. The plated screen is thereafter slipped off the polyvinyl chloride roll, whereby a seamless screen pipe having 160 [.L X 160 1. square apertures is obtained.

The seamless screen pipe thus obtained -was then formed in its surface with a desired pattern by photomechanical process, and the screen pipe was used for screen printing, with useful results of giving distinct contours of the pattern, deep colors, and clear lines.

When fabric was travelled over a distance of 10,000 m in contact with the screen pipe for printing, hardly any change was observed. This indicates that the product has excellent mechanical strength.

EXAMPLE 2 Warp yarns and filling yarns, each of which is a 20 denier, multi-filament silk yarn having a diameter of 45 u, are woven by a hollow weave loom in a plain weave to produce a seamless cylindrical base screen, 1,400 mm in length and 152 mm in outer diameter, in which the warp and filling yarns are spaced apart by 190 u to define square meshes. The base screen is immersed in a 20 percent aqueous solution of sulfuric acid at room temperature for 15 minutes to effect etching. After washing with water the base screen is immersed in an activating bath (so-called catalyst solution) containing 5 g/liter of stannous chloride, 0.3 g/liter of palladium chloride and 100 cc/liter of hydrochloric acid at room temperature for 1 minute, followed by washing with water and subsequent immersion in a 2 percent aqueous solution of sulfuric acid at room temperature for 3 minutes to cause the catalyst palladium to be fixedly deposited on the surface of the screen. The screen is then washed with water and thereafter immersed in a nonelectrolytic nickel plating bath (pH 9.5) containing 30 g/liter of nickel sulfate, 40 g/liter of ammonium I chloride, 15 g/liter of sodium citrate and 20 g/liter of sodium hypophosphite at 47C for 5 minutes to coat the entire front and rear faces of the base screen with a nickel film of about 0.8 p. in thickness. After washing with water, the coated base screen is fitted around a r0- tary Teflon-coated iron roll having an outer diameter of 151 mm, with lead wires fixed to the opposite ends of the base screen respectively and subjected to electroplating in a nickel electroplating bath (pH 5.0) containing 300 g/liter of nickel sulfate, 60 g/liter of nickel chloride, and 55 g/liter of boric acid for minutes, under the conditions of 55C and 5 A/dm to coat the screen with an electroplated nickel film of about 30 p. in thickness. The plated screen is thereafter slipped off the Teflon-coated roll, whereby a seamless screen pipe having 152 p. X 152 p. square apertures is obtained. The product had the same excellent quality as the product obtained in Example 1.

EXAMPLE 3 Warp yarns and filling yarns, each of which is a 16 denier, multi-filament polypropylene yarn having a diameter of 40 u, are woven by a hollow'weave loom in a plain weave to produce a seamless cylindrical base screen, 1,400 mm in length and 152 mm in outer diam-- eter, in which the warp and filling yarns are spaced apart by 200p. to define square meshes. The base screen is immersed, in an aqueous solution of percent of caustic soda and percent of decalin at 50C for 10 minutes to swell the base screen. After washing with water, the screen is further immersed in an aqueous solution containing 10 percent of sulfuric acid and 500 g/lite'r of chromic anhydride at 82C for 20 minutes to effect etching. The base screen is then immersed in a bath containing 30 g/liter of stannous chloride and 40 g/liter of hydrochloric acid at room temperature for 2 minutes to sensitize the screen. After washing with water, the sensitized screen is immersed for activation in a bath containing 0.1 g/liter of palladium chloride and 0.2 cc/liter of hydrochloric acid as the main ingredients at room temperature for 1 minute. The screen is then washed with water and thereafter immersed in a bath (pH 4.5) containing 30 g/liter of nickel sulfate, 20 g/liter of sodium hypophosphite, g/liter of sodium acetate and 15 g/liter of sodium citrate at 80C for 4 minutes to coat the entire front and rear faces of the base screen with a nickel film of about 0.5 p. in thickness. After washing with water, the coated base screen is fitted around a rotary polyvinyl chloride roll having an outer diameter of 151 mm, with lead wires fixed to the opposite ends of the base screen respectively and subjected to electroplating in a bath (pH 4.0) containing 300 g/liter of nickel sulfamate, 5 g/liter of nickel chloride, and g/liter of boric acid for 90 minutes, under the conditions of 50C and 3 A/dm to coat the screen with an electroplated nickel film of about 20 p. in thickness. The plated screen is thereafter slipped off the polyvinyl chloride roll, whereby a seamless screen pipe having 160 p. X 160 ,1. square apertures is obtained. The product had the same excellent quality as the product obtained in Example 1.

EXAMPLE 4 Warp yarns and filling yarns, each of which is a'l6 denier, mono-filament polyamide (nylon N0. 66) yarn having a diameter of 40 u, are woven by a hollow weave loom in a plain weave to produce a seamless cylindrical base screen, 1,400 'mm in length and 152 mm in outer diameter, in which the warp and filling yarns are spaced apart by 200 p. to define square meshes. The base screen is immersed in a 20 percent aqueous solution of formic acid at 35C for 20 minutes to swell the same. After washing with water, the screen is further immersed in an aqueous solution of 5 percent of sulfuric acid and 30 g/liter of chromic anhydride at room .temperature for 5 minutes to effect'etching. The base 1 screen. After washing with water, the sensitized screen 7 is immersed for activation in a bath containing 0.1 g/literof palladium chloride and 0.2 cc/liter of hydrochloric acid as the main ingredients at room temperature for 1 minute. The screen is then washed with water and thereafter immersed in a bath (pH 4.5) containing 30 g/liter of kel l ats n fateaellits f9 1.!.". ..11: pophosphite, 15 g/liter of sodium acetate and 15 g/liter of sodium citrate at C for 4 minutes to coat the entire front and rear faces of the base screen with a nickel film of about 0.5 u in thickness. After washing with water, the coated base screen is fitted around a rotary polyvinyl chloride roll having an outer diameter of 151 mm, with lead wires fixed to the opposite ends of the base screen respectively and subjected to electroplating in a bath (pH '4.0) containing 300 g/liter of nickel sulfamate, 5 g/liter of nickel chloride, and 30 g/liter of boric acid for minutes, under the conditions of 50C and 3 A/dm to coat the screen with an electroplated nickel film of about 20 p. in thickness. The plated screen is thereafter slipped off the polyvinyl chloride roll, whereby a seamless screen pipe having 160 p. X 160 p. square apertures is obtained. The product had the same excellent quality as the product obtained in Example 1 What we claim is:

1. A seamless screen pipe particularly suitable for screen printing of textiles comprising a seamless tubular screen consisting of essentially organic fibers arranged in a reticular configuration having between about -300 mesh per inch, said fibers being spaced apart a distance (H) on one sideof said reticular configuration, and a metal film formed on the surface of the constituent fibers of said tubular screen with the meshes thereof retained, said constituent fibers of said tubular screen being selected from the group consisting of polyester, polyamide and silk filament yarn, with said metal film having a thickness of between about Aato l/lO the distance (H) by which said fibers are spaced apart on one side of said reticular configuration.

2. A seamless screen pipe according to claim 1 wherein said thickness of said metal film is within the range between about 5 to 80 [L- 3. A seamless screen pipe according to claim 1 wherein said tubular screen is in the form of a plain hollow weave. 

1. A SEAMLESS SCREEN PIPE PARTICULARY SUITABLE FOR SCREEN PRINTING OF TEXTILES COMPRISING A SEAMLESS TUBULAR SCREEN CONSISTING OF ESSENTIALLY ORGANIC FIBERS ARRANGED IN A RETICULAR CONFIGURATION HAVING BETWEEN ABOUT 100-300 MESH PER INCH, SAID FIBERS BEING SPACED APART A DISTANCE (H) ON ONE SIDE OF SAID RETICULAR CONFIGURATION, AND A METAL FILM FORMED ON THE SURFACE OF THE CONSTITUENT FIBERS OF SAID TUBULAR SCREEN WITH THE
 2. A seamless screen pipe according to claim 1 wherein said thickness of said metal film is within the range between about 5 to 80 Mu .
 3. A seamless screen pipe according to claim 1 wherein said tubular screen is in the form of a plain hollow weave. 